Most cross-stitch sewing machines have a bed plate for supporting the material and a needle with a cross aperture or eyelet which penetrates the material and then enters a needle opening in the bed plate. The needle opening (where the needle penetrates the plane of the bed plate) in one configuration is through a hole in a feed dog (supported underneath the bed plate) or in a throat plate (supported on a slot on the bed plate), depending on the material feed system utilized. Under the bed plate is a rotating hook sometimes referred to as a looper. The hook may rotate on a vertical or horizontal axis. The hook has mounted in its top a nonrotative bobbin carrier. Between the bobbin carrier and the hook, there is a clearance underneath the bobbin carrier.
When the needle penetrates the material to be sewn, it carries the needle thread to a position underneath the bed plate and then slightly rises. This action causes the needle thread to slightly buckle, allowing it to be engaged by the hook. The hook causes the loop, which is now formed in the needle thread, to be enlarged and for a portion of the loop in the needle thread to come underneath the bobbin carrier. The bobbin carrier contains a spool of bobbin thread which becomes entrapped by the loop of the needle thread. The bobbin thread is carried up to a position adjacent the bottom of the sewn material, forming a pattern of a cross stitch. A more detailed understanding of the workings of cross-stitch sewing machines can be gained from a reading of Landwehr U.S. Pat. No. 3,756,177, Thiel U.S. Pat. No. 5,048,436 and Kessler et al U.S. Pat. No. 4,181,088, the disclosures of which are incorporated herein. At the end of the sewing process, either by manual actuation or by some type of control logic which is monitoring the sewing operation, a rotary or arcuate knife cutter is engaged to cut the bobbin and needle threads.
Most cutters work on the principle of a scissors-type mechanism with movement by a pivotal or rotational arm grabbing the threads and making the threads engage with a stationary knife. To allow the threads which are still connected with the material to be as short as possible and therefore delete or minimize a requirement for a secondary thread cutting operation (after the sewn material has been removed from the sewing machine), it is desirable that the threads at the end of the sewing operation be cut adjacent to the needle opening in the bed plate (which will be a feed dog hole in many industrial, nongarment sewing machines) as much as possible. However, there are two constraints which prevent cutting of the needle thread and bobbin thread adjacent to the needle opening. The first constraint is that the stationary knife typically is located away from the needle opening due to required clearances of moving parts of the sewing machines, including but not limited to the feed dog and hook. Secondly, the portion of the needle thread from the eyelet of the needle to its cut end must be of a minimum length to insure proper operation on the next sewing cycle. Unfortunately, the above two constraints leave a length of the needle thread and the bobbin thread, which are still connected with the sewn material, of the approximate same length as the needle thread which is threaded through the needle eyelet. Therefore, there exists a challenge of providing a sewing machine which can allow an appropriate length of needle thread which is threaded through the needle eyelet after the cutter has cut the needle and bobbin threads and still minimize the length of the needle and bobbin threads which are now connected with the material workpiece which has been sewn.